Tartaric Acid Derivatives in HTHS Fluids

ABSTRACT

The present invention provides high-HTHS value lubricating compositions that have improved fuel economy performance. The present invention also provides methods of operating an internal combustion engine utilizing such compositions. The lubricating compositions of the invention utilize butane dioic imide compounds, such as tartrimides, and may also be low sulfur, low ash and low phosphorus, providing lower wear and friction and improved fuel economy.

BACKGROUND OF THE INVENTION

The present invention relates to a low sulfur, low ash, low phosphoruslubricant composition and method for lubricating an internal combustionengine, providing improved fuel economy and retention of fuel economyand wear and friction reduction, specifically in high temperature highshear (HTHS) fluids, or rather fluids with high HTHS values.

Fuel economy is of great importance, and lubricants which can fosterimproved fuel economy by, for instance, reducing friction within anengine, are of significant value. The present invention provides a lowsulfur, low ash, low phosphorus lubricant compositions for use with highHTHS value oils, which can lead to improved fuel economy in an internalcombustion engine. This improvement is effected by providing an additivepackage in with a high HTHS value fluid in which the friction modifiercomponent is exclusively or predominantly a derivative of ahydroxyl-carboxylic acid, and more specifically a tartrimide or atartramide or combinations thereof.

It is known in the art that fuel economy of vehicles and the HTHS valuesof the lubricant composition used in the vehicle are related. Vehiclesusing lubricant compositions having lower HTHS values exhibit improvedfuel economy. For every SAE Viscosity Grade, a minimum HTHS of thelubricant composition is specified in the SAE J300 Engine Oil ViscosityClassification. Lubricant compositions with higher HTHS values typicallyprovide worse fuel economy performance and are also less sensitive toconventional friction modifiers and other additives often used toimprove fuel economy performance.

There is need for high-HTHS value lubricating compositions that haveimproved fuel economy performance.

SUMMARY OF THE INVENTION

The present invention provides high-HTHS value lubricating compositionsthat have improved fuel economy performance. The present invention alsoprovides methods of operating an internal combustion engine utilizingsuch compositions.

The present invention includes a lubricant composition comprising aderivative of a hydroxyl-carboxylic acid, and more specifically analkoxy or hydroxy substituted succinimide, which may also be referred toas an alkoxy or hydroxy substituted butane dioic imide. In someembodiments the additives is a tartrimide or a tartramide orcombinations thereof. In some embodiments the lubricant compositioncomprises (a) an oil of lubricating viscosity and (b) an alkoxy orhydroxy substituted butane dioic imide friction modifier wherein thefriction modifier is represented by formula I;

wherein R¹ is hydrocarbyl group containing from 8 to 30 or 24 carbonatoms; R² is —H or a hydrocarbyl group; Y is —H, —OH or —OR² with theproviso that when Y is —OR² the two R² groups may be linked to form aring. In some embodiments the additive is an alkyl tartrimide.

The present invention further includes compositions that are low-sulfur,low-phosphorus and low-ash, suitable for use in an internal combustionengine, and/or where the oil of lubricating viscosity is a hightemperature high shear fluid. In some embodiments the lubricantcomposition has a sulfated ash value of up to about 1.0 percent byweight, a phosphorus content of up to about 0.08 percent by weight and asulfur content of up to about 0.4 percent by weight.

The invention further provides a method of lubricating an enginecomprising the steps of: supplying to the engine one or more of thelubricant compositions described herein. In some embodiments the engineis present in an automobile wherein the automobile meets Euro 4 and Euro5 standards.

DETAILED DESCRIPTION OF THE INVENTION

Various preferred features and embodiments will be described below byway of non-limiting illustration.

HTHS values are viscosity measurements and represent a fluid'sresistance to flow under conditions resembling highly-loaded journalbearings in internal combustion engines. The HTHS value of an oil and/orlubricating composition directly correlates to the oil film thickness ina bearing. HTHS values of a fluid may be obtained by using ASTM D4683 at150° C. The lubricating compositions of this invention may have a HTHSvalue of at least 2.9 cP or at least 3.5 cP. In some embodiments thelubricating compositions have the present invention have a HTHS value ofat least 3.5 cP but have fuel economy performance equivalent to alubricating composition that has a HTHS value of about 2.9 and whichdoes not contain the additives described herein.

The present invention provides a composition as described above. Oftenthe composition has total sulfur content in one aspect below 0.4 percentby weight, in another aspect below 0.3 percent by weight, in yet anotheraspect 0.2 percent by weight or less and in yet another aspect 0.1percent by weight or less. Often the major source of sulfur in thecomposition of the invention is derived from conventional diluent oil. Atypical range for the total sulfur content is 0.01 to 0.3 or 0.1 percentby weight.

Often the composition has a total phosphorus content of less than orequal to 800 ppm, in another aspect equal to or less than 500 ppm, inyet another aspect equal to or less than 300 ppm, in yet another aspectequal to or less than 200 ppm and in yet another aspect equal to or lessthan 100 ppm of the composition. A typical range for the totalphosphorus content is 100 to 800 or 500 ppm.

Often the composition has a total sulfated ash content as determined byASTM D-874 of below 1.0 percent by weight, in one aspect equal to orless than 0.7 percent by weight, in yet another aspect equal to or lessthan 0.4 percent by weight, in yet another aspect equal to or less than0.3 percent by weight and in yet another aspect equal to or less than0.05 percent by weight of the composition. A typical range for the totalsulfate ash content is 0.005 to 0.7 or 0.8 percent by weight.

Oil of Lubricating Viscosity

The lubricating compositions of the present invention include an oil oflubricating viscosity. Suitable oils are described below. In someembodiments the specific HTHS values and ranges described above apply tothe oil and/or oils used in the compositions. These HTHS values may alsobe applied to the overall composition, even if one or more of the oilspresent does not have such HTHS values when considered alone.

The oil of lubricating viscosity may include one or more base oils andgenerally makes up a major amount of the overall composition (i.e. anamount greater than about 50 percent by weight). Generally, the oilcomponent is present in an amount greater than about 60 percent, orgreater than about 70 percent, or greater than about 80 percent byweight of the lubricating oil composition. The base oil sulfur contentis typically less than 0.2 percent by weight.

In some embodiment the compositions of the invention include alow-sulfur, low-phosphorus, low-ash lubricating oil component which mayresult in a low-sulfur, low-phosphorus, low-ash lubricating composition.

The low-sulfur, low-phosphorus, low-ash lubricating oil composition mayhave a viscosity of up to about 16.3 mm²/s at 100° C., and in oneembodiment 5 to 16.3 mm²/s (cSt) at 100° C., and in one embodiment 6 to13 mm²/s (cSt) at 100° C. In one embodiment, the lubricating oilcomposition has an SAE Viscosity Grade of 0 W, 0 W-20, 0 W-30, 0 W-40, 0W-50, 0 W-60, 5 W, 5 W-20, 5 W-30, 5 W-40, 5 W-50, 5 W-60, 10 W, 10W-20, 10 W-30, 10 W-40 or 10 W-50, 15 W, 15 W-40 or 15 W-50.

The low-sulfur, low-phosphorus, low-ash lubricating oil composition mayhave a high-temperature/high-shear viscosity at 150° C. as measured bythe procedure in ASTM D4683 of up to 4 mm²/s (cSt), and in oneembodiment up to 3.7 mm²/s (cSt), and in one embodiment 2 to 4 mm²/s(cSt), and in one embodiment 2.2 to 3.7 mm²/s (cSt), and in oneembodiment 2.7 to 3.5 mm²/s (cSt).

The base oil used in any of the compositions described above may be anatural oil, a synthetic oil or a mixture thereof. In some embodimentsit is also provided that the sulfur content of the oils used do notexceed the above-indicated sulfur concentration limits required for theinventive low-sulfur, low-phosphorus, low-ash lubricating oilcomposition. The natural oils that are useful include animal oils andvegetable oils (e.g., castor oil, lard oil) as well as minerallubricating oils such as liquid petroleum oils and solvent treated oracid-treated mineral lubricating oils of the paraffinic, naphthenic ormixed paraffinic-naphthenic types. Oils derived from coal or shale arealso useful.

Synthetic lubricating oils include hydrocarbon oils such as polymerizedand interpolymerized olefins (e.g., polybutylenes, polypropylenes,propylene isobutylene copolymers, etc.); poly(1-hexenes),poly-(1-octenes), poly(1-decenes), etc. and mixtures thereof;alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes,dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g.,biphenyls, terphenyls, alkylated polyphenyls, etc.); alkylated diphenylethers and the derivatives, analogs and homologs thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils that can be used. These are exemplified by the oilsprepared through polymerization of ethylene oxide or propylene oxide,the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g.,methyl-polyisopropylene glycol ether having an average molecular weightof about 1000, diphenyl ether of polyethylene glycol having a molecularweight of about 500-1000, diethyl ether of polypropylene glycol having amolecular weight of about 1000-1500, etc.) or mono- and polycarboxylicesters thereof, for example, the acetic acid esters, mixed C3-8 fattyacid esters, or the carboxylic acid diester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils that can be usedcomprises the esters of dicarboxylic acids (e.g., phthalic acid,succinic acid, alkyl succinic acids, alkenyl succinic acids, maleicacid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipicacid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenylmalonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol,hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol,diethylene glycol monoether, propylene glycol, etc.) Specific examplesof these esters include dibutyl adipate, di(2-ethylhexyl) sebacate,di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecylazelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the2-ethylhexyl diester of linoleic acid dimer, the complex ester formed byreacting one mole of sebacic acid with two moles of tetraethylene glycoland two moles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include those made from C5 to C12monocarboxylic acids and polyols and polyol ethers such as neopentylglycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.

The oil can be a poly-alpha-olefin (PAO). Typically, the PAOs arederived from monomers having from 4 to 30, or from 4 to 20, or from 6 to16 carbon atoms. Examples of useful PAOs include those derived fromoctene, decene, mixtures thereof, and the like. These PAOs may have aviscosity from 2 to 15, or from 3 to 12, or from 4 to 8 mm²/s (cSt), at100° C. Examples of useful PAOs include 4 mm²/s (cSt) at 100° C.poly-alpha-olefins, 6 mm²/s (cSt) at 100° C. poly-alpha-olefins, andmixtures thereof. Mixtures of mineral oil with one or more of theforegoing PAOs may be used.

Unrefined, refined and re-refined oils, either natural or synthetic (aswell as mixtures of two or more of any of these) of the type disclosedhereinabove can be used in the lubricants of the present invention.Unrefined oils are those obtained directly from a natural or syntheticsource without further purification treatment. For example, a shale oilobtained directly from retorting operations, a petroleum oil obtaineddirectly from primary distillation or ester oil obtained directly froman esterification process and used without further treatment would be anunrefined oil. Refined oils are similar to the unrefined oils exceptthey have been further treated in one or more purification steps toimprove one or more properties. Many such purification techniques areknown to those skilled in the art such as solvent extraction, secondarydistillation, acid or base extraction, filtration, percolation, etc.Re-refined oils are obtained by processes similar to those used toobtain refined oils applied to refined oils which have been already usedin service. Such re-refined oils are also known as reclaimed orreprocessed oils and often are additionally processed by techniquesdirected to removal of spent additives and oil breakdown products.

Additionally, oils prepared by a Fischer-Tropsch gas to liquid syntheticprocedure are known and can be used.

Friction Modifier

The additives of the present invention may be classified as frictionmodifiers and provide improved fuel economy performance in the HTHSlubricant compositions in which they are used. The additives may bederivatives of tartaric acid and more specifically are tartrimides. Theadditives may also be descried as alkoxy and/or hydroxy substitutedsuccinimides or even as alkoxy and/or hydroxy substituted butane dioicimides. The compositions of the present invention may also includetartrimides, tartrates, tartrate esters, esteramides and otherderivatives of tartaric acid, in combination with the tartrimidesdescribed herein.

The additive of the present is a friction modifier represented byformula I;

wherein R¹ is hydrocarbyl group containing from 8 to 30 or 24 carbonatoms; R² is —H or a hydrocarbyl group; Y is —H, —OH or —OR² with theproviso that when Y is —OR² the two R² groups may be linked to form aring.

In some embodiments the additive is derived from a material representedby formula II and an amine containing from 8 to 30 or 24 carbon atoms;

wherein R² is a hydrocarbyl group; Y is —H, —OH or —OR² with the provisothat when Y is —OR² the two R² groups may be linked to form a ring.In some embodiments the amine comprises a linear amine containing from16 to 20 carbon atoms. In some embodiments the additive is oleyltartrimide.

The tartrimide additives may be derived by the reaction of tartaric acidand one or more amines, for example, one or more amines having theformula R¹R²NH wherein R¹ and R² each independently represent H, ahydro-carbon-based radical of 1 to 150 carbon atoms provided that thesum of carbon atoms in R¹ and R² is at least 8, or —R³OR⁴ in which R³ isa divalent alkylene radical of 2 to 6 carbon atoms and R⁴ is ahydrocarbyl radical of 5 to 150 carbon atoms. In one embodiment each R¹and R² may contain from 2, 8, or 12 to 100, 50, 26 or 18 carbon atoms.In one embodiment the amine includes oleyl amine.

Examples of the additives of the present invention are preparedconveniently by reacting tartaric acid with one or more of thecorresponding amine. The tartaric acid used for preparing thetartrimides can be the commercially available type (obtained fromSargent Welch), and it is likely to exist in one or more isomeric formssuch as d-tartaric acid, l-tartaric acid, d,l-tartaric acid ormeso-tartaric acid, often depending on the source (natural) or method ofsynthesis (e.g. from maleic acid). These derivatives can also beprepared from functional equivalents to the diacid readily apparent tothose skilled in the art, such as esters, acid chlorides, anhydrides,etc.

The additives of the present invention can be solids, semi-solids, oroils depending on the particular amine used in preparing the tartrimide,or tartramides. For use as additives in oleaginous compositionsincluding lubricating and fuel compositions the tartrimides will have tobe soluble and/or stably dispersible in such oleaginous compositions.Thus, for example, compositions intended for use in oils are oil-solubleand/or stably dispersible in an oil in which they are to be used. Theterm “oil-soluble” as used in this specification and appended claimsdoes not necessarily mean that all the compositions in question aremiscible or soluble in all proportions in all oils. Rather, it isintended to mean that the composition is soluble in an oil (mineral,synthetic, etc.) in which it is intended to function to an extent whichpermits the solution to exhibit one or more of the desired properties.Similarly, it is not necessary that such “solutions” be true solutionsin the strict physical or chemical sense. They may instead bemicro-emulsions or colloidal dispersions which, for the purpose of thisinvention, exhibit properties sufficiently close to those of truesolutions to be, for practical purposes, interchangeable with themwithin the context of this invention.

As previously indicated, the additives of this invention are useful asadditives for lubricants, in which they function primarily as rust andcorrosion inhibitors, friction modifiers, antiwear agents anddemulsifiers. They can be employed in a variety of lubricants based ondiverse oils of lubricating viscosity, including natural and syntheticlubricating oils and mixtures thereof. These lubricants includecrankcase lubricating oils for spark-ignited and compression-ignitedinternal combustion engines, including automobile and truck engines,two-cycle engines, aviation piston engines, marine and railroad dieselengines, and the like. They can also be used in gas engines, stationarypower engines and turbines, and the like. Automatic transmission fluids,transaxle lubricants, gear lubricants, metal-working lubricants,hydraulic fluids and other lubricating oil and grease compositions canalso benefit from the incorporation therein of the compositions of thepresent invention.

Other friction modifiers maybe present in the lubricants of the presentinvention and can include glycerol monooleates, oleyl amides, diethanolfatty amines and mixtures thereof. A useful list of friction modifiersis included in U.S. Pat. No. 4,792,410. In some embodiments thelubricating compositions of the present invention contain the tartaricacid derivatives described above in combination with a secondaryfriction modifier comprising glycerol monooleates, oleyl amides,diethanol fatty amines and/or mixtures thereof.

Fatty acid esters of glycerol can be prepared by a variety of methodswell known in the art. Many of these esters, such as glycerol monooleateand glycerol monotallowate, are manufactured on a commercial scale. Theesters useful for this invention are oil-soluble and are preferablyprepared from C₈ to C₂₂ fatty acids or mixtures thereof such as arefound in natural products. The fatty acid may be saturated orunsaturated. Certain compounds found in acids from natural sources mayinclude licanic acid which contains one keto group. Useful C₈ to C₂₂fatty acids are those of the formula R—COOH wherein R is alkyl oralkenyl.

The fatty acid monoester of glycerol is useful. Mixtures of mono anddiesters may be used. Mixtures of mono- and diester can contain at leastabout 40% of the monoester. Mixtures of mono- and diesters of glycerolcontaining from about 40% to about 60% by weight of the monoester can beused. For example, commercial glycerol monooleate containing a mixtureof from 45% to 55% by weight monoester and from 55% to 45% diester canbe used.

Useful fatty acids are oleic, stearic, isostearic, palmitic, myristic,palmitoleic, linoleic, lauric, linolenic, and eleostearic, and the acidsfrom the natural products tallow, palm oil, olive oil, peanut oil,sunflower oil, soybean oil, rape seed oil or canola oil.

Fatty acid amides have been discussed in detail in U.S. Pat. No.4,280,916. Suitable amides are C₈-C₂₄ aliphatic monocarboxylic amidesand are well known. Reacting the fatty acid base compound with ammoniaproduces the fatty amide. The fatty acids and amides derived therefrommay be either saturated or unsaturated. Important fatty acids includelauric C₁₂, palmitic C₁₆ and stearic C₁₈. Other important unsaturatedfatty acids include oleic, linoleic and linolenic acids, all of whichare C₁₈. In one embodiment, the fatty amides of the instant inventionare those derived from the C₁₈ monounsaturated fatty acids.

The fatty amines and the diethoxylated long chain amines such asN,N-bis-(2-hydroxyethyl)-tallowamine themselves are generally useful ascomponents of this invention. Both types of amines are commerciallyavailable. Fatty amines and ethoxylated fatty amines are described ingreater detail in U.S. Pat. No. 4,741,848.

The lubricating compositions of the present invention may include thefriction modifier additive described above at 0.05 to 5 percent byweight. In some embodiments the additive is present in the compositionfrom 0.05, 0.1, 0.25, or 0.4 to 5.0, 2.0, 1.25, or 1.0 percent byweight. In some embodiments the friction modifier additive describedherein is not borated.

Miscellaneous

Antioxidants (that is, oxidation inhibitors), including hinderedphenolic antioxidants such as 2,6,-di-t-butylphenol, and hinderedphenolic esters such as the type represented by the following formula:

and in a specific embodiment,

wherein R³ is a straight chain or branched chain alkyl group containing2 to 10 carbon atoms, in one embodiment 2 to 4, and in anotherembodiment 4 carbon atoms. In one embodiment, R³ is an n-butyl group. Inanother embodiment R³ can be 8 carbons, as found in Irganox L-135™ fromCiba. The preparation of these antioxidants can be found in U.S. Pat.No. 6,559,105.

Further antioxidants can include secondary aromatic amine antioxidantssuch as dialkyl (e.g., dinonyl) diphenylamine, sulfurized phenolicantioxidants, oil-soluble copper compounds, phosphorus-containingantioxidants, molybdenum compounds such as the Mo dithiocarbamates,organic sulfides, disulfides, and polysulfides (such as sulfurized DielsAlder adduct of butadiene and butyl acrylate). An extensive list ofantioxidants is found in U.S. Pat. No. 6,251,840.

The EP/antiwear agent used in connection with the present invention istypically in the form of a zinc dialkyldithiophosphate. Although thereare an extremely large number of different types of antiwear agentswhich might be utilized in connection with such functional fluids, thepresent inventors have found that zinc dialkyldithiophosphate typeantiwear agents work particularly well in connection with the othercomponents to obtain the desired characteristics. In one embodiment, atleast 50% of the alkyl groups (derived from the alcohol) in thedialkyldithiophosphate are secondary groups, that is, from secondaryalcohols. In another embodiment, at least 20%, 35% or even 50% of thealkyl groups are derived from C3-C4 alcohols, is some embodimentsisopropyl alcohol.

Ashless detergents and dispersants depending on their constitution mayupon combustion yield a non-volatile material such as boric oxide orphosphorus pentoxide. However, ashless detergents and dispersants do notordinarily contain metal and therefore do not yield a metal-containingash on combustion. Many types of ashless dispersants are known in theart. Such materials are commonly referred to as “ashless” even thoughthey may associate with a metal ion from another source in situ.

“Carboxylic dispersants” are reaction products of carboxylic acylatingagents (acids, anhydrides, esters, etc.) containing at least 34 andpreferably at least 54 carbon atoms which are reacted with nitrogencontaining compounds (such as amines), organic hydroxy compounds (suchas aliphatic compounds including monohydric and polyhydric alcohols, oraromatic compounds including phenols and naphthols), and/or basicinorganic materials. These reaction products include imide, amide, andester reaction products of carboxylic ester dispersants.

The carboxylic acylating agents include fatty acids, isoaliphatic acids(e.g. 8-methyl-octadecanoic acid), dimer acids, addition dicarboxylicacids 4+2 and 2+2 addition products of an unsaturated fatty acid with anunsaturated carboxylic reagent), trimer acids, addition tricarboxylicacids (Empol® 1040, Hystrene® 5460 and Unidyme® 60), and hydrocarbylsubstituted carboxylic acylating agents (from olefins and/orpolyalkenes). In one embodiment, the carboxylic acylating agent is afatty acid. Fatty acids generally contain from 8 up to 30, or from 12 upto 30 or 24 carbon atoms. Carboxylic acylating agents are taught in U.S.Pat. Nos. 2,444,328, 3,219,666, 4,234,435 and 6,077,909.

The amine may be a mono- or polyamine. The monoamines generally have atleast one hydrocarbyl group containing from 1 to 30 or 24 carbon atoms,or from 1 to 12 carbon atoms. Examples of monoamines include fatty(C8-30) amines (Armeens™), primary ether amines (SURFAM® amines),tertiary-aliphatic primary amines (Primenes™), hydroxyamines (primary,secondary or tertiary alkanol amines), ether N-(hydroxyhydrocarbyl)amines, and hydroxyhydrocarbyl amines (Ethomeens™ and Propomeens™). Thepolyamines include alkoxylated diamines (Ethoduomeens™), fatty diamines(Duomeens™), alkylenepolyamines (ethylenepolyamines), hydroxy-containingpolyamines, polyoxyalkylene polyamines (Jeffamines™), condensedpolyamines (a condensation reaction between at least one hydroxycompound with at least one polyamine reactant containing at least oneprimary or secondary amino group), and hetero-cyclic polyamines. Usefulamines include those disclosed in U.S. Pat. No. 4,234,435 (Meinhart) andU.S. Pat. No. 5,230,714 (Steckel).

The polyamines from which the dispersant is derived include principallyalkylene amines conforming, for the most part, to the formula

wherein t is an integer typically less than 10, A is hydrogen or ahydrocarbyl group typically having up to 30 carbon atoms, and thealkylene group is typically an alkylene group having less than 8 carbonatoms. The alkylene amines include principally methylene amines,ethylene amines, hexylene amines, heptylene amines, octylene amines,other polymethylene amines. They are exemplified specifically by:ethylene diamine, diethylene triamine, triethylene tetramine, propylenediamine, decamethylene diamine, octamethylene diamine,di(heptamethylene) triamine, tripropylene tetramine, tetraethylenepentamine, trimethylene diamine, pentaethylene hexamine,di(trimethylene) triamine. Higher homologues such as are obtained bycondensing two or more of the above-illustrated alkylene amines likewiseare useful. Tetraethylene pentamines is particularly useful.

The ethylene amines, also referred to as polyethylene polyamines, areespecially useful. They are described in some detail under the heading“Ethylene Amines” in Encyclopedia of Chemical Technology, Kirk andOthmer, Vol. 5, pp. 898-905, Interscience Publishers, New York (1950).

Hydroxyalkyl-substituted alkylene amines, i.e., alkylene amines havingone or more hydroxyalkyl substituents on the nitrogen atoms, likewiseare useful. Examples of such amines include N-(2-hydroxyethyl)ethylenediamine, N,N″-bis(2-hydroxyethyl)-ethylene diamine,1-(2-hydroxyethyl)-piperazine, monohydroxypropyl)-piperazine,di-hydroxypropyl-substituted tetra-ethylene pentamine,N-(3-hydroxypropyl)-tetra-methylene diamine, and2-heptadecyl-1-(2-hydroxyethyl)-imidazoline.

Higher homologues, such as are obtained by condensation of theabove-illustrated alkylene amines or hydroxy alkyl-substituted alkyleneamines through amino radicals or through hydroxy radicals, are likewiseuseful. Condensed polyamines are formed by a condensation reactionbetween at least one hydroxy compound with at least one polyaminereactant containing at least one primary or secondary amino group andare described in U.S. Pat. Nos. 5,230,714 and 5,296,154 (Steckel).

Examples of these “carboxylic dispersants” are described in BritishPatent 1,306,529 and in many U.S. patents including the following: U.S.Pat. Nos. 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022,3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743,3,632,511, 4,234,435, 6,077,909 and 6,165,235.

Succinimide dispersants are a species of carboxylic dispersants. Theyare the reaction product of a hydrocarbyl substituted succinic acylatingagent with an organic hydroxy compound or, an amine containing at leastone hydrogen attached to a nitrogen atom, or a mixture of said hydroxycompound and amine. The term “succinic acylating agent” refers to ahydrocarbon-substituted succinic acid or succinic acid-producingcompound (which term also encompasses the acid itself). Such materialstypically include hydrocarbyl-substituted succinic acids, anhydrides,esters (including half esters) and halides.

Succinic based dispersants have a wide variety of chemical structuresincluding typically structures such as

In the above structure, each R¹ is independently a hydrocarbyl group,such as a polyolefin-derived group having an M _(n) of 500 or 700 to10,000. Typically the hydrocarbyl group is an alkyl group, frequently apolyisobutylene group derived from PIB having a molecular weight of 500or 700 to 5000, or alternatively 1500 or 2000 to 5000. Alternativelyexpressed, the R¹ groups can contain 40 to 500 carbon atoms, forinstance at least 50, e.g., 50 to 300 carbon atoms, such as aliphaticcarbon atoms. The R² are alkylene groups, commonly ethylene (C₂H₄)groups. Such molecules are commonly derived from reaction of an alkenylacylating agent with a polyamine, and a wide variety of linkages betweenthe two moieties is possible beside the simple imide structure shownabove, including a variety of amides and quaternary ammonium salts.Succinimide dispersants are more fully described in U.S. Pat. Nos.4,234,435, 3,172,892 and 6,165,235.

The polyalkenes from which the substituent groups are derived aretypically homopolymers and interpolymers of polymerizable olefinmonomers of 2 to 16 carbon atoms; usually 2 to 6 carbon atoms. Theamines which are reacted with the succinic acylating agents to form thecarboxylic dispersant composition can be monoamines or polyamines asdescribed above.

The succinimide dispersant is referred to as such since it normallycontains nitrogen largely in the form of imide functionality, althoughit may be in the form of amine salts, amides, imidazolines as well asmixtures thereof. To prepare the succinimide dispersant, one or more ofthe succinic acid-producing compounds and one or more of the amines areheated, typically with removal of water, optionally in the presence of anormally liquid, substantially inert organic liquid solvent/diluent atan elevated temperature, generally in the range of 80° C. up to thedecomposition point of the mixture or the product; typically 100° C. to300° C.

Additional details and examples of the procedures for preparing thesuccinimide dispersants of the present invention are included in, forexample, U.S. Pat. Nos. 3,172,892, 3,219,666, 3,272,746, 4,234,435,6,440,905 and 6,165,235.

“Amine dispersants” are reaction products of relatively high molecularweight aliphatic halides and amines, preferably polyalkylene polyamines.Examples thereof are described, for example, in the following U.S. Pat.Nos. 3,275,554, 3,438,757, 3,454,555, and 3,565,804.

“Mannich dispersants” are the reaction products of alkyl phenols inwhich the alkyl group contains at least 30 carbon atoms with aldehydes(especially formaldehyde) and amines (especially polyalkylenepolyamines). The materials described in the following U.S. patents areillustrative: U.S. Pat. Nos. 3,036,003, 3,236,770, 3,414,347, 3,448,047,3,461,172, 3,539,633, 3,586,629, 3,591,598, 3,634,515, 3,725,480,3,726,882, and 3,980,569.

Post-treated dispersants are obtained by reacting carboxylic, amine orMannich dispersants with reagents such as dimercaptothiadiazoles, urea,thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids,hydrocarbon-substituted succinic anhydrides, nitriles epoxides, boroncompounds, phosphorus compounds or the like. Exemplary materials of thiskind are described in the following U.S. Pat. Nos. 3,200,107, 3,282,955,3,367,943, 3,513,093, 3,639,242, 3,649,659, 3,442,808, 3,455,832,3,579,450, 3,600,372, 3,702,757, and 3,708,422.

Polymeric dispersants are interpolymers of oil-solubilizing monomerssuch as decyl methacrylate, vinyl decyl ether and high molecular weightolefins with monomers containing polar substituents, e.g., aminoalkylacrylates or acrylamides and poly-(oxyethylene)-substituted acrylates.Examples of polymer dispersants thereof are disclosed in the followingU.S. Pat. Nos. 3,329,658, 3449,250, 3,519,656, 3,666,730, 3,687,849, and3,702,300.

The composition can also contain one or more detergents, which arenormally salts, and specifically overbased salts. Overbased salts, oroverbased materials, are single phase, homogeneous Newtonian systemscharacterized by a metal content in excess of that which would bepresent according to the stoichiometry of the metal and the particularacidic organic compound reacted with the metal. The overbased materialsare prepared by reacting an acidic material (typically an inorganic acidor lower carboxylic acid, preferably carbon dioxide) with a mixturecomprising an acidic organic compound, a reaction medium comprising atleast one inert, organic solvent (such as mineral oil, naphtha, toluene,xylene) for said acidic organic material, a stoichiometric excess of ametal base, and a promoter.

In some embodiments the lubricating compositions of the presentinvention include the tartaric acid derivatives described above incombination with one or more detergents, and in some embodiments incombination with an overbased salt detergent.

The acidic organic compounds useful in making the overbased compositionsof the present invention include carboxylic acids, sulfonic acids,phosphorus-containing acids, phenols or mixtures thereof. Preferably,the acidic organic compounds are carboxylic acids or sulfonic acids withsulfonic or thiosulfonic groups (such as hydrocarbyl-substitutedbenzenesulfonic acids), and hydrocarbyl-substituted salicylic acids.Another type of compound useful in making the overbased composition ofthe present invention is salixarates. A description of the salixaratesuseful for of the present invention can be found in publication WO04/04850.

The metal compounds useful in making the overbased salts are generallyany Group 1 or Group 2 metal compounds (CAS version of the PeriodicTable of the Elements). The Group 1 metals of the metal compound includeGroup 1a alkali metals (e.g., sodium, potassium, lithium) as well asGroup 1b metals such as copper. The Group 1 metals are preferablysodium, potassium, lithium and copper, preferably sodium or potassium,and more preferably sodium. The Group 2 metals of the metal base includethe Group 2a alkaline earth metals (e.g., magnesium, calcium, strontium,barium) as well as the Group 2b metals such as zinc or cadmium.Preferably the Group 2 metals are magnesium, calcium, barium, or zinc,preferably magnesium or calcium, more preferably calcium.

The amount of excess metal in the detergent is commonly expressed interms of metal ratio. The term “metal ratio” is the ratio of the totalequivalents of the metal to the equivalents of the acidic organiccompound. A neutral metal salt has a metal ratio of one. A salt having4.5 times as much metal as present in a normal salt will have metalexcess of 3.5 equivalents, or a ratio of 4.5. The metal ratio for asulfonate detergent is calculated based on the ratio of metal to thesulfonate functionality, ignoring the presence of any other incidentalacidic groups that may be present in the detergent molecule. The metalratio of the sulfonate detergents used in the present invention willtypically be at least 3, at least 10 or even at least 16. In someembodiments the metal ratio may be from 3, 8, 10, 15 or 16 up to 35 or30 or 25 or 20.

Examples of the overbased detergent of the present invention include,but are not limited to calcium sulfonates, calcium phenates, calciumsalicylates, calcium salixarates and mixtures thereof. In someembodiments the overbased detergent is a sulfonate, or more specificallya calcium sulfonate, such as a alkylbenzenesulfonate detergent, whereinthe sulfonate is derived from predominantly linear alcohols or othercompounds. That is, the alkyl group of the sulfonate is derived frompredominantly linear alcohols or other compounds. That is not to say thealkyl group may not contain a branch point, as often a linear group willattach at the number 2 position on the chain, leaving a methylsubstituent group. In other words the alkyl group referred to here maybe linear in the sense that it is a linear alkyl group attached to thebenzene or toluene ring at any location along the linear alkyl chain,such as the 2, 3 or 4 position, and this connection point, albeit not atthe 1 position, does not result in the group bring non-linear.

The amount of the overbased material, that is, the detergent, ifpresent, is in one embodiment 0.05 to 3 percent by weight of thecomposition, or 0.1 to 3 percent, or 0.1 to 1.5 percent, or 0.15 to 1.5percent by weight.

Anti-foam agents used to reduce or prevent the formation of stable foaminclude silicones or organic polymers. Examples of these and additionalanti-foam compositions are described in “Foam Control Agents”, by HenryT. Kerner (Noyes Data Corporation, 1976), pages 125-162.

The compositions of the present invention are employed in practice aslubricants by supplying the lubricant to an internal combustion engine(such as a stationary gas-powered internal combustion engine) in such away that during the course of operation of the engine the lubricant isdelivered to the critical parts of the engine, thereby lubricating theengine.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbylgroup” is used in its ordinary sense, which is well-known to thoseskilled in the art. Specifically, it refers to a group having a carbonatom directly attached to the remainder of the molecule and havingpredominantly hydrocarbon character. Examples of hydrocarbyl groupsinclude: hydrocarbon substituents, that is, aliphatic (e.g., alkyl oralkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, andaromatic-, aliphatic-, and alicyclic-substituted aromatic substituents,as well as cyclic substituents wherein the ring is completed throughanother portion of the molecule (e.g., two substituents together form aring); substituted hydrocarbon substituents, that is, substituentscontaining non-hydrocarbon groups which, in the context of thisinvention, do not alter the predominantly hydrocarbon nature of thesubstituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy,mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); heterosubstituents, that is, substituents which, while having a predominantlyhydrocarbon character, in the context of this invention, contain otherthan carbon in a ring or chain otherwise composed of carbon atoms.Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituentsas pyridyl, furyl, thienyl and imidazolyl. In general, no more than two,preferably no more than one, non-hydrocarbon substituent will be presentfor every ten carbon atoms in the hydrocarbyl group; typically, therewill be no non-hydrocarbon substituents in the hydrocarbyl group.

It is known that some of the materials described above may interact inthe final formulation, so that the components of the final formulationmay be different from those that are initially added. For instance,metal ions (of, e.g., a detergent) can migrate to other acidic oranionic sites of other molecules. The products formed thereby, includingthe products formed upon employing the composition of the presentinvention in its intended use, may not be susceptible of easydescription. Nevertheless, all such modifications and reaction productsare included within the scope of the present invention; the presentinvention encompasses the composition prepared by admixing thecomponents described above.

EXAMPLES

The invention will be further illustrated by the following examples,which set forth particularly advantageous embodiments. While theexamples are provided to illustrate the present invention, they are notintended to limit it.

Five example lubricants (Examples 1 to 5) are prepared using aformulation designed to meet ACEA C3-08 specifications. Each example wasformulated to have a HTHS value of at or above 3.5 cP and a kinematicviscosity at 100 C of about 11.7 cSt. All of the lubricants use YubaseGroup III base oils in combination with Nexbase PAO Group IV base oil ina ratio of about 85:15 by ratio. All five lubricants include the sameadditive package, which designed to provide a lubricant that meets thespecifications listed above. The additive package (including theviscosity modifier) is present in each example at 28 percent by weightof the overall composition. Each example, except for a baseline, is thentreated with 0.5% or 0.25% by weight of a unique friction modifieradditive. The balance of each of the examples is the base oil mixturedescribed above. The formulations of the examples are summarized in thetable below.

TABLE I Example Formulations Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Base- Compar-Compar- Compar- Inven- line ative ative ative tive Base Oil 72.0 71.7571.5 71.5 71.5 Additive Package 28.0 28.0 28.0 28.0 28.0 AlkylTartrimide — — — — 0.5 Alkyl Tartrate — — 0.5 — — Glycerol — 0.25 — 0.5— Monooleate

The samples are evaluated using the HFRR test, which is a standardindustry test for wear. The test employs apparatus as described in ASTMD-6079. The test measures the coefficient of friction provided by thelubricant under the testing conditions, while ramping the temperaturefrom 40 to 160 C. The results of the testing are summarized in the tablebelow:

TABLE II HFRR Results Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Base- Compar- Compar-Compar- Inven- line ative ative ative tive Average Wear 168 171 165 137102 Scar Diameter (um) Average Coeff of 0.147 0.146 0.161 0.162 0.103Friction over Ramp

The results show that the compositions of the present invention provideunexpected improvement in the wear performance of the lubricatingcompositions compared to the same compositions without the frictionmodifier additive as well as the same compositions that containdifferent friction modifier additives. The inventive example has asmaller average wear scar and a lower average coefficient of frictionthan any of the other examples.

The examples are also evaluated using the MTM (mini-traction machine)test, which is used to measure traction and friction over a range ofloads and speeds. The test is completed with 36 Newtons of load, a speedof 3000 to 10 mm/s, 50% slide to roll ratio, under isothermal conditionsat 40, 60, 80, 100, 120 and 140 C. Lower results indicate betterperformance. The tables below summarize the results with Table III-3providing the results at low speed.

TABLE III-1 MTM Results at 2000 mm/s 2000 mm/s 40 C. 60 C. 80 C. 100 C.120 C. 140 C. Ex 1 0.0439 0.0392 0.0328 0.0262 0.0206 0.0161 Ex 2 0.04380.0391 0.0327 0.0262 0.0208 0.0167 Ex 3 0.0437 0.0389 0.0326 0.02620.0206 0.0162 Ex 4 0.0437 0.0391 0.0329 0.0264 0.0206 0.0159 Ex 5 0.04430.0395 0.0330 0.0267 0.0212 0.0168

TABLE III-2 MTM Results at 200 mm/s 200 mm/s 40 C. 60 C. 80 C. 100 C.120 C. 140 C. Ex 1 0.0510 0.0423 0.0348 0.0304 0.0299 0.0348 Ex 2 0.05130.0427 0.0363 0.0333 0.0345 0.0425 Ex 3 0.0506 0.0421 0.0351 0.03020.0287 0.0332 Ex 4 0.0504 0.0424 0.0352 0.0302 0.0275 0.0273 Ex 5 0.05220.0432 0.0370 0.0367 0.0409 0.0436

TABLE III-3 MTM Results at 20 mm/s 200 mm/s 40 C. 60 C. 80 C. 100 C. 120C. 140 C. Ex 1 0.0561 0.0556 0.0578 0.0634 0.0721 0.0838 Ex 2 0.05700.0597 0.0642 0.0695 0.0805 0.0909 Ex 3 0.0566 0.0571 0.0595 0.06430.0703 0.0883 Ex 4 0.0576 0.0579 0.0616 0.0660 0.0714 0.0780 Ex 5 0.05960.0603 0.0640 0.0672 0.0673 0.0669

The results show that at low speeds (boundary lubrication conditions)and high temperatures (specifically 120 C and 140 C) the compositionsdescribed herein provide a significant reduction in traction coefficientcompared to both the baseline and the fully formulated compositions thatuse different friction modifiers.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about.” Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil, which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.Similarly, the ranges and amounts for each element of the invention canbe used together with ranges or amounts for any of the other elements.As used herein, the expression “consisting essentially of” permits theinclusion of substances that do not materially affect the basic andnovel characteristics of the composition under consideration.

What is claimed is:
 1. A lubricant composition comprising (a) an oil oflubricating viscosity; (b) an alkoxy or hydroxy substituted butane dioicimide friction modifier wherein the friction modifier is represented byformula I;

wherein R¹ is hydrocarbyl group containing from 8 to 30 carbon atoms; R²is —H or a hydrocarbyl group; Y is —H, —OH or —OR² with the proviso thatwhen Y is —OR² the two R² groups may be linked to form a ring.
 2. Thelubricant composition of claim 1 wherein the composition is alow-sulfur, low-phosphorus and low-ash lubricant suitable for use in aninternal combustion engine; and wherein the oil of lubricating viscosityis a high temperature high shear fluid.
 3. The lubricant composition ofclaim 1 wherein the lubricant composition is a high temperature highshear fluid having a dynamic viscosity of at least 3.5 cP.
 4. Thecomposition of claim 1 wherein component (b) is derived from a materialrepresented by formula II and an amine containing from 8 to 30 carbonatoms;

wherein R² is a hydrocarbyl group; Y is —H, —OH or —OR² with the provisothat when Y is —OR² the two R² groups may be linked to form a ring. 5.The composition of claim 4 wherein the amine comprises a linear aminecontaining from 16 to 20 carbon atoms.
 6. The composition of claim 1further comprising an additional friction modifier other than component(b), an overbased detergent, or combinations thereof.
 7. The compositionof claim 1 wherein component (b) comprises oleyl tartrimide.
 8. A methodof lubricating an engine comprising the steps of: I. supplying to theengine a lubricant composition comprising: (a) an oil of lubricatingviscosity; (b) an alkoxy or hydroxy substituted butane dioic imidefriction modifier wherein the friction modifier is represented byformula I;

wherein R¹ is hydrocarbyl group containing from 8 to 24 carbon atoms; R²is a hydrocarbyl group; Y is —H, —OH or —OR² with the proviso that whenY is —OR² the two R² groups may be linked to form a ring.
 9. The methodof claim 8 wherein the engine is present in an automobile wherein theautomobile meets Euro 4 and Euro 5 standards.
 10. The method of claim 8wherein the lubricant composition is a low-sulfur, low-phosphorus andlow-ash lubricant suitable for use in an internal combustion engine; andwherein the oil of lubricating viscosity is a high temperature highshear fluid.
 11. The method of claim 8 wherein the lubricant compositionis a high temperature high shear fluid having a dynamic viscosity of atleast 3.5 cP.
 12. The method of claim 8 wherein component (b) is derivedfrom a material represented by formula II and an amine containing from 8to 30 carbon atoms;

wherein R² is a hydrocarbyl group; Y is —H, —OH or —OR² with the provisothat when Y is —OR² the two R² groups may be linked to form a ring. 13.The method of claim 12 wherein the amine comprises a linear aminecontaining from 16 to 20 carbon atoms.
 14. The method of claim 8 whereinthe lubricant composition further comprises an additional frictionmodifier other than component (b), an overbased detergent, orcombinations thereof.
 15. The method of claim 8 wherein component (b)comprises oleyl tartrimide.